reserve T for TopSpace,
  A, B for Subset of T;

theorem :: Theorem 1
  A is subcondensed implies A` is supercondensed
proof
A1: (Cl A)` = Int A` by TDLAT_3:3;
  assume A is subcondensed;
  then
A2: (Cl Int A)` = (Cl A)`;
  (Cl Int A)` = Int ((Int A)`) by TDLAT_3:3
    .= Int (Cl A`) by TDLAT_3:2;
  hence thesis by A2,A1;
end;
